Haploinsufficiency for DNA methyltransferase 3A predisposes hematopoietic cells to myeloid malignancies
Christopher B. Cole, … , Christopher A. Miller, Timothy J. Ley
Christopher B. Cole, … , Christopher A. Miller, Timothy J. Ley
Published September 5, 2017
Citation Information: J Clin Invest. 2017;127(10):3657-3674. https://doi.org/10.1172/JCI93041.
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Research Article Hematology Oncology

Haploinsufficiency for DNA methyltransferase 3A predisposes hematopoietic cells to myeloid malignancies

Abstract

The gene that encodes de novo DNA methyltransferase 3A (DNMT3A) is frequently mutated in acute myeloid leukemia genomes. Point mutations at position R882 have been shown to cause a dominant negative loss of DNMT3A methylation activity, but 15% of DNMT3A mutations are predicted to produce truncated proteins that could either have dominant negative activities or cause loss of function and haploinsufficiency. Here, we demonstrate that 3 of these mutants produce truncated, inactive proteins that do not dimerize with WT DNMT3A, strongly supporting the haploinsufficiency hypothesis. We therefore evaluated hematopoiesis in mice heterozygous for a constitutive null Dnmt3a mutation. With no other manipulations, Dnmt3a+/– mice developed myeloid skewing over time, and their hematopoietic stem/progenitor cells exhibited a long-term competitive transplantation advantage. Dnmt3a+/– mice also spontaneously developed transplantable myeloid malignancies after a long latent period, and 3 of 12 tumors tested had cooperating mutations in the Ras/MAPK pathway. The residual Dnmt3a allele was neither mutated nor downregulated in these tumors. The bone marrow cells of Dnmt3a+/– mice had a subtle but statistically significant DNA hypomethylation phenotype that was not associated with gene dysregulation. These data demonstrate that haploinsufficiency for Dnmt3a alters hematopoiesis and predisposes mice (and probably humans) to myeloid malignancies by a mechanism that is not yet clear.

Authors

Christopher B. Cole, David A. Russler-Germain, Shamika Ketkar, Angela M. Verdoni, Amanda M. Smith, Celia V. Bangert, Nichole M. Helton, Mindy Guo, Jeffery M. Klco, Shelly O’Laughlin, Catrina Fronick, Robert Fulton, Gue Su Chang, Allegra A. Petti, Christopher A. Miller, Timothy J. Ley

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Figure 5

Dnmt3a+/– mice develop myeloid malignancies after a long latent period.

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Dnmt3a+/– mice develop myeloid malignancies after a long latent period....
(A) Kaplan-Meier plot of survival data from littermate-matched Dnmt3a+/– (n = 43) and Dnmt3a+/+ (n = 20) mice that were monitored in a 2-year tumor watch. Mice that became moribund were euthanized for pathologic analysis. (B) After 2 years, all remaining mice were bled for CBCs and euthanized. All mice were grouped by spleen size into Dnmt3a+/+, clinically unaffected Dnmt3a+/–, and affected (moribund) Dnmt3a+/– mice (see Results for details). Affected Dnmt3a+/– mice exhibited anemia and thrombocytopenia, but not significant leukocytosis. *P < 0.05; ***P < 0.001, 1-way ANOVA with Bonferroni’s correction for multiple testing. (C) Distribution of pathologic diagnoses according to Bethesda criteria for all mice that could be definitively classified (n = 16). (D) Representative histology of tissues from affected Dnmt3a+/– mice. Scale bars: 20 μm; 200 μm (low mag).